This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The purpose of this project is to perform biochemical characterization of proteins that modulate the activity of channels important for pain sensation. The targets of study will include channel cytoplasmic domains, small molecule modulators, peptide modulators, and associated membrane or cytoplasmic proteins. The objective is to purify proteins, determine molecular interaction sites, and perform structural studies.The UCSF mass spectrometry facility will aid us in determining the accurate mass and of purified products, as well as confirming the identity of purified products. The aid of the facility will also allow us to interpret results from chemical crosslinking studies in the future.